The Maps inside Your Head


September 30, 2014 - 1:00pm
NW 243
About the Speaker
Vijay Balasubramanian (University of Pennsylvania)

In many functionally distinct regions of the brain, populations of neurons form maps of sensory and cognitive spaces.   I will discuss approaches to understanding the organization of such maps.  First I will consider a sensory example -- the visual system -- and discuss how the challenge of processing a diverse and unpredictable world with limited neural resources shapes the the distribution of cell types and circuit architectures.   I will then apply insights gained from "seeing" to a cognitive example -- the "sense of place" -- i.e., the representation, by the grid cell system in the entorhinal cortex, of an animal's physical location in terms of a set of lattices with different spatial scales.   The theory predicts many architectural features of the grid system (e.g., the fixed ratio between grid scales) which match recent experimental data.     Finally I will use similar reasoning in another sensory system -- the sense of smell -- to predict how olfactory receptors and downstream  circuits should reorganize to be well-adapted to varying olfactory environments.    Each of these examples suggest that brains have evolved neural circuits that exploit sophisticated principles of mathematics –- principles that scientists have only recently discovered.  I will conclude with some general thoughts about the organization of maps in the brain based on these three examples of seeing, placing, and smelling.